The present invention relates to an adduct of hydrogen peroxide, sodium sulphate and potassium chloride, to a process for its preparation and to the use of this adduct.
An adduct of the formula 4Na.sub.2 SO.sub.4.2H.sub.2 O.sub.2.NaCl is known from DE-OS No. 25 30 539. This adduct is prepared by allowing sodium sulphate to react with hydrogen peroxide at a concentration of 70 to 800 g/l in aqueous solution in the presence of sodium chloride at a concentration of 20 to 300 g/l and at a temperature between 0.degree. and 50.degree. C. In this process a relatively high hydrogen peroxide concentration must be used when the sodium chloride concentration is low and vice versa.
As a crystallographic examination shows (J.C.S. Chem. Comm. 1978, p. 288-9), the adduct has a clathrate structure: H.sub.2 O.sub.2 is incorporated in a cage formed from sulphate-oxygen atoms. The Na ions of the adduct do not have a uniform coordination. Whereas 8 of the 9 Na ions are each surrounded by 5 oxygen atoms and 1 choride ion in a distorted octahedral arrangement, the ninth Na ion is surrounded by oxygen atoms in a tetragonal prismatic arrangement. On the whole, the adduct therefore has a rather complicated structure. The mutual arrangement and coordination of the ions of sodium, sulphate and chlorine is alone capable of forming the voids (cages) which exactly match the dimensions of the H.sub.2 O.sub.2 modecule and which account for the stability of the clathrate.
It was to be expected that the substitution of one type of ion by another, a fourth type, particularly a larger type of ion, would not allow the complex cage structure to form or else would expand the cage structure and drastically reduce the stability of the clathrate. Indeed, no indication at all can be derived from DE-OS No. 25 30 539 that such a modification might be possible. The expectation that the incorporation of a fourth type of ion would not lead to the formation of stable adducts is confirmed by the above-mentioned literature reference taken from J.C.S. Chem. Comm., according to which all attempts to incorporate other alkali metal halides in the complex have failed.